Résumé
Purpose: Exosomes are small vesicles which are released by cells into body fluids. We have demonstrated the presence of circulating exosomes with viral antigens in lung transplant recipients (LTxRs) diagnosed with respiratory viral infections. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection results Covid-19 disease and SARS-CoV2 infection of LTxRs can be severe with poor clinical outcomes. The goal of this single center study is to determine the development of antibody responses specific to SARS-CoV2 in LTxRs, characterize the immune and molecular markers in the circulating exosomes induced and its role in eliciting immunity. Method(s): To determine that antibody responses and induction of circulating exosomes we enrolled LTxRs with SARS-CoV2 infection (n=50), following 2 doses of vaccination (n=100). Exosomes were isolated from plasma by exosome precipitation kit followed by 0.2 micron filtration and size determination by NanoSight300. Exosomes were subjected to transmission electron microscopy for spike (CSP) and nucleocapsid (CNP) antigens. Exosomes were also characterized by western blot for immune and molecular markers (NFkB, CIITA, 20S proteasome, beta catenin and VWF). C57BL/6 mice were immunized with circulating exosomes isolated from LTxRs with infection. Result(s): 78% of SARS-CoV2 infected LTxRs developed antibodies to CSP and CNP as opposed to normal infected individuals. In contrast, only 55% vaccinated LTxRs developed antibodies to SARS-CoV2 spike. Exosomes from SARS-CoV2 infected and vaccinated individuals contained CSP S2, CNP and immune and molecular markers. Transmission electron microscopy also revealed the presence of CSP and CNP on exosomes. C57BL/6 mice immunized with exosomes carrying CSP developed antibodies to SARS-CoV2 spike antigens. Severe inflammation and lung lesions were also demonstrated in the lungs of mice immunized with exosomes carrying CSP. Conclusion(s): In conclusion, we demonstrated that SARS-CoV2 infected and vaccinated LTxRs induced circulating exosomes with SARS-CoV2 CSP. In addition, exosomes contained important immune activating molecules suggesting that the exosomes induced by SARS-CoV2 may have a physiological role in inducing immune responses. Immunization of mice with exosomes from SARS-CoV2 infected and vaccinated LTxRs not only induced SARS-CoV2 spike specific antibody but also resulted in inflammation and lung lesions in the immunized animals.
Résumé
Introduction: Ivermectin is an antiparasitic agent that has demonstrated antiviral potential against HIV1, Dengue, Zika viruses and most recently, COVID-19. But the rampant self-medication and off-label use for COVID prophylaxis in some countries is cause for concern. Here, we present what may be the first reported case of ANCAassociated vasculitis(AAV)from Ivermectin use. Case Description: A 56-year male with no significant past medical history presented with dark urine, epistaxis, conjunctival redness, arthralgias, and malaise. His mother was on dialysis for the past few years for ESRD of unknown etiology. For several months, he had been taking Ivermectin imported from Peru for COVID prophylaxis per family advice. He was on no other medications. His creatinine, normal at baseline, was now 4.5mg/dL. He had hematuria, 3g/d proteinuria, dysmorphic RBCs and RBC casts. Serum C3, C4, ANA, anti-dsDNA, anti-GBM, hepatitisB&C screen, SPEP&UPEP were negative. Atypical and p-ANCA were negative, but c-ANCA was 1:640. Kidney biopsy revealed pauci-immune necrotizing crescentic glomerulonephritis. He soon developed pulmonary hemorrhages. Ivermectin was discontinued. He received prednisone 1mg/kg, 3 biweekly doses of intravenous cyclophosphamide, 10 doses of plasmapheresis, and was initiated on dialysis. Four weeks later, he has no epistaxis or pulmonary hemorrhages and is off oxygen. He does remain dialysis-dependent. Discussion: Drug exposure can trigger ANCA formation against myeloperoxidase(MPO) and, less commonly, proteinase 3(PR3). Drug-associated AAV can't be discerned from primary AAV based on clinical and pathological findings. Clues suggesting drug-associated AAV include a temporal relationship of symptom onset with suspected drug, a high ANCA titer, and positive autoantibodies like elastase and lactoferrin. Drug-associated AAV has a better prognosis than its primary counterpart, with symptoms often resolving with drug withdrawal. Though this may not suffice in cases with pulmonary and renal involvement, outcomes in drug-associated AAV remain comparable even with shorter induction and often no maintenance regimens. Commonly implicated drugs are hydralazine, levamisole-contaminated cocaine, propylthiouracil, allopurinol. Although no case of Ivermectin-induced AAV has been reported, we recommend a high index of suspicion as prompt cessation of the offending drug can significantly improve prognosis in drug-associated AAV.